


The Greatest Betrayal

by LigerCat



Category: Phineas and Ferb
Genre: Best Friends, Betrayal, Crack, Emotional Hurt, F/M, Gen, Immature "Adults", Post-Episode: s04e47 Act Your Age
Language: English
Status: Completed
Published: 2019-10-30
Updated: 2019-10-30
Packaged: 2021-01-13 12:15:55
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 460
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/21243935
Author URL: https://archiveofourown.org/users/LigerCat/pseuds/LigerCat
Summary: It didn't matter that they were going to tell him, he wasn't sure he could ever look at them the same again.





	The Greatest Betrayal

**Author's Note:**

> Don't own.

"Phineas..."

"No. No. No." Phineas went to point a finger at his brother but it ended up being more of a strange flapping motion. "I don't want to hear anything about it." He squeezed his eyes shut. "You know what we should have invented? Brain bleach. Or some type of memory eraser. Gah, I want that image out of my head!"

"Phineas."

"No, Ferb." Phineas opened his eyes, glancing at him before quickly looking away as _that_ image flooded his mind again. It was something he would have never expected to walk in on. At first, he thought it was a misunderstanding, because it couldn't possibly be what it looked like.

It couldn't be.

Except it was.

"We were going to tell you."

Shaking his head, Phineas clasped his hands over his ears. Nope. He didn't want to hear it. If Ferb wasn't blocking the door of their old room, he'd leave the house. He didn't even want to be around his sibling or her.

He wasn't sure he would ever be able to look at them the same way again.

Since he was facing away with his ears plugged, he didn't know Ferb had walked over to him until his hands were pulled away from his head. Ferb kept a strong grip on his arms as he turned Phineas to face him.

Phineas refused to look at him. "I can't believe you. You have a girlfriend and you--" He couldn't say it. He could barely think it.

"Vanessa was perfectly okay with what I did."

"Just... why her?" That's what got Phineas. Out of everyone, why her?

"She was there, I was there." Ferb shrugged. "One thing led to another..."

In horror, Phineas turned away again.

"We're both adults."

Nineteen was not an adult as far as he was concerned. He didn't even consider himself an adult, and he was twenty. "That's not the point." Shaking his head, he sighed. "I'm sorry, Ferb, but you broke my trust." He shook a shaky breath. "You and Isabella both."

A groan from the doorway made both brothers look.

"Oh my gosh." Isabella rolled her eyes. "It's just a _movie_, Phineas."

"But you promised we'd all go together!" Phineas knew he was whining, but he'd been looking forward to go to the new Space Adventure movie with his best friends. They'd been planning to since they heard about the movie.

"And we still can."

"No, we can't because you already watched it!" In a moment of pettiness, Phineas got the great idea to create a device that would erase all early-viewing websites from the internet. He stored the idea away for later.

"Then we'll watch it again," Ferb soothed, letting go of his arms.

Phineas sniffed. It just wouldn't be the same.

**Author's Note:**

> This was not going to be about a movie, but the "We're both adults" line, my fingers refused to continue with the original plot. So I wrote the first thing that came to mind for the ending.


End file.
